Method for measuring automobile horsepower and its application on chassis dynamometers

Abstract

The present invention provides a more accurate device and method for measuring automobile horsepower, specifically the internal combustion engine, ICE horsepower at the crankshaft, or the electric motor(s') horsepower, or the combined ICE and electric motor(s') horsepower. It applies to automobiles that do not incorporate, or can disengage, regenerative braking, RGB. The proposed device and method measures horsepower in real road test conditions, through the utilization of an accelerometer that performs measurements of the automobile velocity, acceleration and deceleration, whereas the method provided may be also applied to chassis dynamometers, resulting into a more accurate horsepower measurement by such dynamometers.

What is claimed is: 
     
       1. A method for measuring automobile horsepower, for an internal combustion engine or hybrid automobile having a four-stroke engine not incorporating the cylinder deactivation technology, the method comprising:
 steadily mounting into the automobile a mobile device including GPS connection, an accelerometer and a mobile device application operatively coupled to each other, 
 performing an acceleration phase by accelerating the automobile in real road conditions on a flat and horizontal road with a selected gear and measuring using the accelerometer acceleration and velocity of the automobile during the acceleration phase of the automobile, 
 immediately after acceleration phase of the automobile, performing a deceleration phase by decelerating the automobile in real road conditions with the same selected gear as the one used during the acceleration phase of the automobile and measuring using the accelerometer deceleration and velocity of the automobile during the deceleration phase of the automobile, and 
 calculating automobile horsepower P e  using the mobile device application and measured acceleration, deceleration and velocity during the acceleration and deceleration phases according to the following equation:
     P   e =ME mv [ dv/dt (acc)+ dv/dt (dec)] 
 
 wherein: ME is the mechanical efficiency of the automobile powerplant, m is the total mass of the automobile including passengers and cargo, v is the measured automobile velocity, dv/dt(acc) is the measured automobile acceleration, dv/dt(dec) is the measured automobile deceleration, and t is time. 
 
     
     
       2. The method according to  claim 1 , wherein the ME values for different types of powerplants have as follows:
 naturally aspirated gasoline engine: 0.85 
 turbocharged gasoline engine: 0.91 
 supercharged gasoline engine: 0.89 
 naturally aspirated diesel engine: 0.89 
 turbocharged diesel engine: 0.94 
 hybrid, naturally aspirated gasoline engine: 0.87 
 hybrid, turbocharged gasoline engine: 0.94 
 hybrid, supercharged gasoline engine: 0.93 
 hybrid, turbocharged diesel engine: 0.96. 
 
     
     
       3. A method for measuring automobile horsepower; from the measured automobile torque on a chassis dynamometer for an internal combustion engine or hybrid automobile having a four-stroke engine not incorporating the cylinder deactivation technology, on chassis dynamometers on which deceleration is possible with the same selected gear as the one with which acceleration on these chassis dynamometers is performed, the method comprising:
 performing an acceleration phase by accelerating the automobile on the rollers of the chassis dynamometer with a selected gear and measuring a first resultant torque exerted on the rollers of the chassis dynamometer during the acceleration phase of the automobile;
 immediately after the acceleration phase of the automobile, performing a deceleration phase by decelerating the automobile on the rollers of the chassis dynamometer with the same selected gear as the one used during the acceleration phase of the automobile and measuring a second resultant torque exerted on the rollers of the chassis dynamometer during the deceleration phase of the automobile; and 
 calculating automobile torque T e  using the first and second resultant torque according to the following equation:
     T   e =ME( T   acc   +T   dec ), 
 
 wherein ME is the mechanical efficiency of the automobile powerplant, T acc  is the first resultant torque and T dec  is the second resultant torque. 
 
 
     
     
       4. The method according to  claim 3 , wherein the ME values for different types of powerplants have as follows:
 naturally aspirated gasoline engine: 0.85 
 turbocharged gasoline engine: 0.91 
 supercharged gasoline engine: 0.89 
 naturally aspirated diesel engine: 0.89 
 turbocharged diesel engine: 0.94 
 hybrid, naturally aspirated gasoline engine: 0.87 
 hybrid, turbocharged gasoline engine: 0.94 
 hybrid, supercharged gasoline engine: 0.93 
 hybrid, turbocharged diesel engine: 0.96.